Eye protection devices typically have a fixed optical transmission which reduced the intensity of light, incident on the eye protection device, that reaches the eyes of a user of the eye protection device. Thus there is a fixed attenuation of the incident light. For example, sun glasses typically have a fixed shade, i.e., a fixed transmission. Sun glasses are available which change transmitivity from a clear to a darker state in response to the intensity of the incident light based on a chemical response of constituents in the lens. Such sun glasses have the disadvantage that change from the clear to the dark state is fixed by the chemical process. That is, the user of the sun glasses cannot select the degree of transmission that the sun glasses have in response to a given incident intensity of light. The degree of transmission in response to a given intensity of light is set by the amount of the chemically active agent in the sun glasses that is fixed at manufacture and it, thus, cannot subsequently be changed by the user. Moreover, the chemical process of change from the clear to the dark state and visa versa is slow. Furthermore, the color of the dark state is fixed.
Applicant's invention provides a solution to this problem. According to applicants invention the degree of change in optical transmission from a clear to a dark state can be controlled by the user. Thus different users can select the degree of transmission that is suitable to them. Also, the same user may find it desirable to have a different degree of transmission in different environments. For example, for a given incident intensity of light a user may desire a greater degree of attenuation of the light intensity at a beach than while walking on a city street. Moreover, according to applicant's invention the change from the clear to the dark state and visa versa is rapid. Thus, for example, is driving an automobile on a sunny day and enters a tunnel the transmission can change rapidly from the dark to the clear state when entering the tunnel and rapidly from the clear to the dark state when exiting the tunnel. In addition, according to applicant's invention the color of the lens can be selected by the user from a large variety of colors. Thus a user can, depending on the circumstances, select a different color for a different occasion.